Drop buy TechPowerUp for a dissection of a common PSU for PCs. The sticker on the side of mosty PSUs warns about opening the casing as there are no "user serviceable parts" inside. We all know that to be a lie, as long as you let the capacitors bleed out their charge before touching them with anything metal.

"The objective of this article is to give detailed, but easy to understand information about the most crucial part of a PC system, the Power Supply Unit. Follow us into this journey to the PSU territory and we promise you that you will gain valuable knowledge."